Question 1

Half-value layer (HVL) is defined as the thickness of a designated absorber required to

Accepted Answer

HVL is the thickness of an absorber required to reduce the intensity of the primary beam by half or 50%. Therefore, option A is the correct choice.

Question 2

Patient dose decreases when

Accepted Answer

High-speed radiographic film used in combination with high-speed intensifying screens requires less radiation to produce an image, thus decreasing patient dose.

Question 3

Which of the following is the best type of gonadal shield to use during a sterile field procedure?

Accepted Answer

A shadow shield is ideal for sterile field procedures as it does not come into contact with the patient or the sterile field, thus maintaining sterility.

Question 4

Which of the following will best reduce radiation exposure to the patient?

Accepted Answer

Using rare-earth screens will increase the speed of the film system, reducing the amount of radiation exposure needed to produce a diagnostic image. Using non-screen film would result in a higher radiation exposure to the patient. Decreasing kVp would result in higher patient exposure due to the need for a higher mAs setting. Increasing mAs would also result in higher patient exposure.

Question 5

The minimum source-to-tabletop distance permitted in mobile fluoroscopy is

Accepted Answer

The minimum source-to-tabletop distance permitted in mobile fluoroscopy is 12 inches, as stated in the Code of Federal Regulations (CFR), Title 21, Part 1020.31(b)(3). This distance is necessary to ensure that the operator and others in the vicinity of the machine are not exposed to excessive amounts of radiation. Therefore, the correct answer is C.

Question 6

A fluoroscope must be equipped with a cumulative timing device which times the radiation exposure and sounds an audible alarm after the fluoroscope has been energized for

Accepted Answer

According to the FDA, a fluoroscope must be equipped with a cumulative timing device which times the radiation exposure and sounds an audible alarm after the fluoroscope has been energized for five minutes.

Question 7

The function of a filter is to remove which of the following from the x-ray beam?

Accepted Answer

Filters are used in x-ray machines to remove long wavelength radiation from the x-ray beam because these longer wavelengths have less penetrating power and contribute more to patient dose than to image formation.

Question 8

Which of the following is not a type of beam limitation device?

Accepted Answer

Filters are not used as beam limitation devices, they are used to modify the quality of the beam by attenuating certain energies. Collimators, cones, and aperture diaphragms are all types of beam limitation devices.

Question 9

A computed radiography (CR) system includes the following:
1. storage phosphor cassettes
2. a storage phosphor reader
3. bar code scanner
4. remote operator panel for entering patient date 5. a clinical workstation for reviewing and printing

Accepted Answer

A computed radiography (CR) system includes all of the components listed, including storage phosphor cassettes, a storage phosphor reader, a bar code scanner, a remote operator panel for entering patient data, and a clinical workstation for reviewing and printing. Therefore, the correct choice is D, which includes all of the listed components.

Question 10

CR photostimulable phosphor cassettes use _____, which causes the screens to fluoresce upon exposure to ionizing radiation from the x-ray tube.

Accepted Answer

CR photostimulable phosphor cassettes use europium-activated barium fluorohalide crystals, which fluoresce upon exposure to ionizing radiation from the x-ray tube. Option A refers to a different type of dosimeter, option B refers to a type of dosimeter used in personal radiation monitoring, and option D refers to a type of phosphor used in rare earth imaging screens.

Question 11

The minimum source-to-tabletop distance permitted for fixed fluoroscopes is

Accepted Answer

The minimum source-to-tabletop distance for fixed fluoroscopes is 15 inches (38 cm). This distance is determined by federal regulations to ensure patient safety and minimize radiation exposure.

Question 12

To within what percent of the SID must the collimator light and actual irradiated area be accurate?

Accepted Answer

The collimator light and actual irradiated area must be accurate to within 2% of the SID (source-to-image distance) for optimal image quality and patient safety. Any larger discrepancy can result in unacceptable levels of image distortion, decreased resolution, and increased radiation exposure.

Question 13

The number of repeat radiographs can be reduced by

Accepted Answer

The answer of The number of repeat radiographs can be...

Question 14

Which of the following combinations would reduce patient radiation dose during an x-ray exam?

Accepted Answer

Higher kVp allows for lower mAs, which reduces patient dose. Increased filtration removes low-energy photons that do not contribute to image formation but increase patient dose.

Question 15

The greatest beam limitation is accomplished when the cone/cylinder is _____, and the diameter opening is _____.

Accepted Answer

The greatest beam limitation is achieved when the cone or cylinder is longer, which helps in narrowing down the beam, and the diameter opening is smaller, further limiting the spread of the beam. This combination ensures that the beam is focused and limited to a specific area, reducing scatter radiation and improving image quality.

Question 16

How much total filtration is required when using over 70 kVp?

Accepted Answer

When using over 70 kVp, the total filtration required is 2.5 mm of aluminum (Al) equivalent. This is a standard requirement to ensure patient safety by reducing the dose of soft radiation.

Question 17

The tabletop exposure rate during fluoroscopy shall not exceed

Accepted Answer

The answer of The tabletop exposure rate during fluoroscopy shall...

Question 18

Which of the following exposure techniques will provide the least amount of radiation exposure to the patient?

Accepted Answer

The amount of radiation exposure to the patient is directly related to the milliampere-seconds (mAs) and inversely related to the kilovoltage peak (kVp). Lower mAs and higher kVp settings result in less radiation exposure. Among the options, 50 mAs and 90 kVp (Option A) will provide the least amount of radiation exposure because it has the lowest mAs and the highest kVp.

Question 19

The fundamental difference between computed radiography and conventional analog imaging is the replacement of film-screens with

Accepted Answer

Computed radiography uses photostimulable phosphor plates instead of traditional film-screen techniques. Option A and B refer to types of dosimeters which are not used for image capture. Option D is not a commonly used term in radiography.

Question 20

Which of the following is the most versatile type of x-ray beam limitation device?

Accepted Answer

The collimator is the most versatile type of x-ray beam limitation device because it can shape the beam into a variety of different sizes and shapes to accommodate different imaging needs. Aperture diaphragms, cones, and cylinders are all limited in their ability to shape the beam in as many ways as a collimator can.

Quiz 7: Protection of Patients